(Newser)
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Authorities in Phoenix say it definitely fits the definition of terrorism: Somebody has been shooting at vehicles along a downtown stretch of Interstate 10 and there have now been 10 incidents in the space of 11 days with no arrests made, CNN reports. The head of the Arizona Department of Public Safety says there's a "real and continued" threat to motorists and that people will be hurt or killed if it keeps up. "Any time you have multiple shootings against American citizens on a highway, that's terrorism," says Col. Frank Milstead, per NBC News. "They're trying to frighten or kill somebody." He has urged drivers to be "hypervigilant."

So far, the only person injured has been a 13-year-old girl cut on the ear when a bullet went through the windshield of an SUV. The Department of Public Safety has asked for the public's help, although it has released very few details in order to protect the investigation, the Arizona Republic reports. Officials have declined to use the word "sniper" and used the word "projectiles" instead of "bullets" when discussing the most recent incidents. The Republic notes that Phoenix has been through similar terror in the past: Over 15 months in 2005 and 2006, two men firing guns out of car windows during joyrides killed eight people and at least 10 dogs and horses.